1. Field of Endeavor
The present invention relates to separators and more particularly to a precision gap particle separator.
2. State of Technology
U.S. Pat. No. 5,425,802 to Robert M. Burton, et al. assigned to The United States of America as represented by the Administrator of Environmental Protection Agency and President and Fellows of Harvard, patented Jun. 20, 1995, provides background information regarding a virtual impactor for removing particles from an airstream. The virtual impactor comprises nozzle means for accelerating an entering airstream, particle receiving means positioned downstream from the nozzle means, and a chamber in fluid communication with the gap between the nozzle means and the receiving means. The nozzle means comprises an inlet and an elongated outlet having a width dimension of between about 0.007 and 0.010 inches, and further having a longitudinal axis normal to and passing through the center of the elongated outlet. The particle receiving means comprises an elongated inlet having a width dimension of between about 0.013 and 0.015 inches and an outlet and further has a longitudinal axis normal to and passing through the center of the elongated inlet. The particle receiving means is positioned downstream from the outlet of the nozzle means so that the flow gap therebetween is between about 0.008 and 0.012 inches, and is further positioned so that the longitudinal axis of the nozzle means and the longitudinal axis of the receiving means are substantially coaxial and so that the width dimension of the nozzle means outlet and the width dimension of the receiving means inlet are substantially parallel. The chamber is configured to be in fluid communication with a vacuum source, as is the outlet of the particle receiving means.
U.S. Pat. No. 5,040,424 to Virgil A. Maple, et al., assigned to Regents of the University of Minnesota, patented Aug. 20, 1991, provides background information regarding a high-volume aerosol sampling inlet housing which provides smooth inlet flow to a 10 micron classification device in a high volume flow. The high volume sampler with which the inlet is used establishes a high flow, for example, 40 cubic feet per minute. The air flow into the inlet has a standard 40 cubic feet per minute leading to the high volume sampler which requires a secondary inlet flow of about two cubic feet per minute needed for particle classification. The two cubic feet per minute flow is exhausted at a separate outlet and is not connected to the standard high volume sampler. Thus, a total flow of 42 cubic feet per minute enters the inlet. The entrance opening to the inlet is an annular opening below a dome cover. Screens are provided to keep any bugs or large debris from entering the inlet housing. The debris-free air flow is passed through the desired impactor device, and the large particles will be collected with the secondary outlet flow of only two cubic feet per minute while the smaller particles are carried out by the major flow of 40 cfm to the high volume sampler filter placed below. The larger particles are thus inertially separated from the major flow and are flushed by the smaller secondary or minor flow. The major flow through to the high volume sampler is maintained at the standard 40 cubic feet per minute. The particles in the inlet air stream are separated into size classifications larger and smaller than 10 microns. The large particles that are flushed out with the two cubic feet per minute flow can either be removed from the air stream by a second filter, or analyzed in a conventional impactor or some other device, or may be allowed to pass through the air pump and be blown back into the atmosphere.
U.S. Pat. No. 5,183,481 to William Felder, assigned to Aerochem Research Laboratories, Inc., patented Feb. 2, 1993, provides background information regarding a supersonic virtual impactor. A supersonic gas flow is employed with a virtual impactor to separate fine particles completely from the gas. The carrying gas and fine particles are accelerated to supersonic speeds and then impacted against a virtual impactor. When the supersonic stream strikes the virtual impactor, a shock wave forms in the gas stream near the impactor surface. The carrying gas turns sharply away while the particles in the gas stream, carried by their inertia, continue in their original direction and pass into the virtual impactor. On the downstream side of the virtual impactor surface, a non-contaminating inert gas maintains a pressure equal to or greater than the pressure of the carrying gas between the virtual impactor surface and the shock wave.
U.S. Pat. No. 6,402,817 to Warner Bergman, assigned to the Regents of the University of California, patented Jun. 11, 2002, provides background information regarding a low pressure drop, multi-slit virtual impactor. A virtual impactor system is provided for dividing a particle containing gas flow into (a) a small flow component with a small portion of the gas flow that carries particles essentially greater than a predetermined size and (b) a large flow component with a large portion of the gas flow that carries particles essentially less than the predetermined size. The gas can be either air or other gases. The virtual impactor system can also utilize fluids other than gas, for example, liquids. The virtual impactor system includes multiple nozzles for accelerating and channeling the fluid stream and multiple receivers positioned downstream from the nozzles. The nozzles are located so that each receiver has a substantially common axis with a corresponding nozzle. The receivers are separated from the nozzles by gaps. The virtual impactor system also includes multiple exhaust chambers in fluid communication with the gaps between the nozzles and the receivers. The multiple exhaust chambers are sandwiched alternately between the multiple receivers. The nozzles have an elongated outlet, with the nozzle outlet positioned to direct the accelerated fluid flow into the receivers in an approximate straight line.
Features and advantages of the present invention will become apparent from the following description. Applicants are providing this description, which includes drawings and examples of specific embodiments, to give a broad representation of the invention. Various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this description and by practice of the invention. The scope of the invention is not intended to be limited to the particular forms disclosed and the invention covers all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.
The present invention provides a method of producing a particle separator for separating particles entrained in a fluid. Some of the particles are of a small size, smaller than a predetermined size, and some of the particles are of a large size, larger than said predetermined size. A first channel and a second channel are etched in a base. A precision gap is etched in the base connecting the first channel and the second channel. The precision gap is etched to a size that allows the small particles to pass from the first channel into the second channel and prevents the large particles from passing from the first channel into the second channel. A cover is positioned over the base unit, the first channel, the precision gap, and the second channel. An input port is connected to the first channel for directing the fluid containing the entrained particles into the first channel. An output port is connected to the first channel for directing the large particles out of the first channel. A port is connected to the second channel for directing the small particles out of the second channel.
The present invention provides a system for separating particles entrained in a fluid. Some of the particles are of a relative small size, smaller than a predetermined size, and some of the particles are of a relative large size, larger than said predetermined size. The system comprises a base, a first channel in the base, a second channel in the base spaced from and substantially parallel to the first channel, and a precision gap connecting the first channel and the second channel. The precision gap is of a size that allows the small particles to pass from the first channel into the second channel and prevents the large particles from passing from the first channel into the second channel. A cover is positioned over the base, the first channel, the precision gap, and the second channel. An input port connected to the first channel directs the fluid containing the entrained particles into the first channel. An output port connected to the first channel directs the large particles out of the first channel. A port connected to the second channel directs the small particles out of the second channel.
The invention is susceptible to modifications and alternative forms. Specific embodiments are shown by way of example. It is to be understood that the invention is not limited to the particular forms disclosed. The invention covers all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.